The subject matter disclosed herein relates to electric power generation and distribution, and more particularly to direct current (DC) electric power systems having active damping.
Electrical power systems in hybrid vehicles, such as military hybrid vehicles, can include high voltage direct current power generation and distribution systems. Such electrical systems, however, can experience stability problems. Constant power loads, such as a switched mode power converter may introduce a destabilizing effect on a DC bus, causing significant voltage oscillation. The source ripple filter must attenuate rectification ripple and current harmonics resulting from active rectifier switching. The input filter of a switching power converter must provide forward voltage attenuation of alternating current (AC) voltage superimposed on a DC bus voltage, attenuate current harmonics resulting from power converter switching and those injected into DC bus to allowed levels, and have a low output impedance so as not to adversely affect the stability of switched-mode power converter. A power converter's input LC filter without a damper introduces possible instability in the presence of constant power (i.e., negative impedance) loads. Traditionally LC or RC damping networks are used to stabilize unstable loads. The LC damper is connected in series with the inductor of the input LC filter, while an RC damper is connected in parallel with the capacitor of the input LC filter. The size of damping networks is considerably larger than the input LC filter itself, and can therefore be difficult to manage.